Purpose: In infants, temperature assessment is crucial in determining diagnostic interventions and treatment regimes. False-low temperature readings may lead to fatal consequences and false-high temperature readings can lead to costly work-ups. The purpose of this study was to determine the accuracy of fever detection with tympanic-membrane thermometers (TMT) in birth to under seven months as compared to glass mercury rectal thermometers (RT). The physiological framework viewed the rectal temperature as current practice "gold standard" for indirect measurement of core temperature. This framework also included critical factors potentially important to TMT accuracy for which literature review indicated need for further research (age, behavior, medications).

Design/Setting: The descriptive-correlational design was conducted in a Level III urban emergency department where 1% of 52,000 annual visits represented the studyÆs population.

Sample: From November 1997 to February 1998 (all shifts and days), 102 infants met the inclusion criteria: less than seven months, medical conditions, hemodynamically stable (no emergent life-threatening conditions), and without rectal/otic anomalies.

Methodology: Paired TMT and RT measurements were recorded with age, antipyretic use and infant behaviors on standardized forms. Review of staffÆs TMT/RT knowledge and direct observations assured correct techniques. The five TMTs used were evaluated weekly for accuracy and recalibrated as needed.

Results: The 102 infants studied were divided into 64 younger infants (<4 months) and 38 older infants (4 to <7 months). Overall Pearson correlation between TMT and RT readings regardless of fever state was 0.78. Sensitivity of TMT in identifying febrile states (defined as <100.5 degrees F with "gold standard" RT), was 85% of all infants, 80% in younger and 87% in older. Importantly, TMT-identified "fevers" were incorrect (false positives with RT <100.5 degrees F) 50% of the time in younger infants (7% in older; 23% overall). No effects on TMT accuracy were found for behavior or potential differential downward tympanic-temperature shift by antipyretics.

Conclusions: TMT accurately detects non-fever states in all infants and fever from 4 months. In infants <4 months, TMT can be used for initial screening. For TMT temperature >99.6 degrees F (equivalent to RT>100.5 degrees F), reassessment using RT should be done to avoid unnecessary fever-related diagnostic testings. [Research Paper Presentation]